M. Heydari-Malayeri - Paris Observatory

The angle between the light entering and exiting
the prism when the light passing through the prism is parallel to the
prism's base. Angle of minimum deviation (D) is used to
measure the → index of refraction (n)
of the prism glass, because:
n = sin [(A + D)/2]/sin (A/2),
where A is the → prism angle.

A period from about 1645 to 1715 when the number of → sunspots
was unusually low. This → solar activity
minimum is attested also through the increased content of carbon
14 in tree rings in that period. The reason is that the cosmic rays which
produce 14C reach the Earth in a greater number when there is
weak solar activity (see also → radiocarbon dating).
The Maunder minimum occurred during a period of cooling of the Earth,
called the → Little Ice Age.
The Maunder minimum is one of a number of periods of low solar activity, including the
→ Dalton minimum,
the → Sporer minimum,
the → Wolf minimum , and
the → Oort minimum.

After the British astronomer Edward Walter Maunder (1851-1928) who,
along with Gustav Spörer of Germany, first called attention to this phenomenon;
→ minimum.

minimum

کمینه

kaminé (#)

Fr.: minimum

The least value attained (or attainable) by a function; the opposite of maximum.

A period of low → solar activity that lasted from about
A.D. 1420 to 1570. It occurred before → sunspots had been
studied, and was discovered by analysis of the proportion of carbon-14 in tree rings,
which is strongly correlated with solar activity.

A period of low → solar activity that lasted from about
A.D. 1420 to 1570. It occurred before → sunspots had been
studied, and was discovered by analysis of the proportion of carbon-14 in tree rings,
which is strongly correlated with solar activity.